In an agreement signed Jan. 24 in Munich, the companies said part of that co-development would focus on lightweight technologies for vehicle bodies, "using cutting-edge materials such as reinforced composites."

Those technologies could be used both on a jointly developed sports car or other BMW and Toyota cars.

Munich-based BMW has been in the forefront of developing carbon-fiber composites for the auto industry, with a proprietary process that will be used on its own i-series electric cars. The BMW i3 is slated to hit the market later this year, to be followed by the i8.

Toyota, based in Toyota City, Japan, has been in the lead of using fuel cells to power an electric drivetrain. It has test vehicles already on the road, and has announced plans to sell a fuel-cell sedan in limited markets in 2015. Fuel-cell stacks use a variety of thermoplastic and thermoset materials, including the film at the heart of every cell.

"[Toyota] and the BMW Group share the same strategic vision of future sustainable mobility," said Norbert Reithofer, chairman of the BMW board of management, in a press release. "In light of the technological changes ahead, the entire automotive industry faces tremendous challenges, which we also regard as an opportunity.

"This collaboration is an important building block in keeping both companies on a successful course in the future."

Toyota and BMW previously signed a memorandum of understanding to work together in other lightweight-vehicle developments. The new agreement takes the process further, covering four key development areas: fuel cells, a sports car platform, lightweight materials and "post lithium-ion battery" technology.

In fuel cells, the companies will take aim not only at a fuel-cell stack, but also a tank to hold hydrogen used to power those cells. They will jointly develop the codes and standards needed in a hydrogen infrastructure to place hydrogen fuel stations where needed.

A feasibility study will be conducted this year on a joint platform for a midsize sports vehicle, which will include the lightweight technologies and composites study.

In addition, the firms agreed to combine research on a future battery system called a "lithium air battery" that promises a higher energy density than current systems. A lithium air system uses a different chemistry than the mix in a lithium-ion battery, and also uses air from the surrounding environment.

"We are entering the phase [under the agreement] that promises the fruit," said Akio Toyoda, president of Toyota. "While placing importance on what we learn from the joint development, we will work hard together in reaching our common goal of making ever-better cars."